The present invention broadly relates to embroidering machines and, more specifically, pertians to a new and improved construction of a borer apparatus for an embroidering machine.
In its more particular aspects the present invention relates to a borer apparatus for an embroidering machine. The borer apparatus comprises means for the removable mounting of at least one exchangeable borer implement on a borer support member or support, such as a borer beam or a borer rail of the embroidering machine. The mounting means also secures the exchangeable borer implement against inadvertent rotation. Each exchangeable borer implement is inserted with its shaft into a sliding or close fitting bore in the borer support. A first stop member projecting into the close fitting bore cooperates with a slot in the shaft of the exchangeable borer implement to secure the shaft of such exchangeable borer implement against inadvertent rotation.
A substantial problem with borer apparatuses of the aforementioned type consists in constructing the mount of the exchangeable borer implement on the embroidering machine in such a manner that the cutting edges of the borers are precisely vertically and horizontally oriented and such that all borer tips, with respect to their lengths and their positions, are stationarily or fixedly positioned to a precision of fractions of millimeters in order that qualitatively superior merchandise can be manufactured.
Optimally this can be achieved if all borer implements are permanently screwed into the borer support or rail of the machine and are all ground or sharpened together in the borer support or rail. However, such fixed arrangements permit neither an efficient or economical pattern change nor a suitable replacement or exchange of the borer implements. Furthermore, such arrangements are in stark contrast to modern designs of embroidering machines with embroidering station engagement means for activating and deactivating any desired combination of embroidering stations.
So-called exchangeable borer implement arrangements for achieving or effecting a better pattern change as well as for achieving or effecting an easier replacement or exchange of exchangeable borer implements have proved successful. In these arrangements, each exchangeable borer implement is inserted with its shaft into a close fitting bore formed in the borer support or beam or in the borer rail and is secured by a suitable means against inadvertent rotation and inadvertent axial movement.
This type of exchangeable borer implement arrangement is known from the Swiss Patent No. 580,188 in which close fitting bores for the acceptance of an exchangeable borer implement are each formed in an associated one of a number of sockets threaded or screwed to and adjusted in the borer support or beam or in the borer rail. The cylindrical shaft of each exchangeable borer implement is plugged or inserted into this associated socket. A C-shaped leaf spring loop, retaining the threaded shaft of the borer socket and which is held in frictional engagement onto the borer support by the screw of the screwed or threaded-in socket, serves to fix or secure the inserted exchangeable borer implement against inadvertent rotation and inadvertent axial movement. A free-standing, outwardly bent or angled shank of the C-shaped leaf spring loop grips or surrounds the exchangeable borer implement in positive engagement and under spring tension in the area of its base. For this purpose, the exposed shank of the C-shaped leaf spring loop features a notch which corresponds to the profile of the exchangeable borer implement at the contact point or location of the C-shaped leaf spring clip.
An exchangeable borer implement arrangement is known from Swiss Patent No. 103,867 in which close fitting bores for the acceptance of an exchangeable borer implement are each formed in a respective one of a number of screwed-in sockets in the borer support or beam or in the borer rail. However, these close fitting bores are not cylindrical as in the aforementioned known arrangement, but are conical. Correspondingly, the exchangeable borer implements in this latter known arrangement are equipped with conical borer shafts. Each exchangeable borer implement features two recesses or flats on the base or shank which are used when inserting and adjusting the exchangeable borer implement as well as when releasing the conical connection between the exchangeable borer implement and the socket by means of a key which engages the locations between these two recesses.
A yet further exchangeable borer implement arrangement known in practical operation provides, for each exchangeable borer implement, a stud which is connected with a borer support or beam or with a borer rail in a suitable manner, e.g. in this case, screwed-in cylindrical studs are provided for each exchangeable borer implement onto which the respective exchangeable borer implement can be plugged by means of a corresponding complementing bore in its shaft. A pivotable spring, featuring a clamping shank, engages the exchangeable borer implement and fixes or secures it against rotary and axial movement on the borer support or beam or rail. The protection against inadvertent rotation is implemented here in that the spring engages, with its clamping shank or member, a sloping surface of a cross or diagonal groove on the shaft of the exchangeable borer implement.
These known arrangements can only very limitedly fulfill the required conditions, namely the precise positioning of the exchangeable borer implement under all operational conditions and especially also after long periods of use. The relatively short thread of the sockets for the plug connector as well as the additional plug connector between the socket and the exchangeable borer implement are causes of intolerable inaccuracies in the positioning of the exchangeable borer implement along the longitudinal axis. Additionally, the known types of protection against inadvertent rotation are less than adequate, whether they function by means of a clamping spring engaging a cross or diagonal groove in the shaft of the exchangeable borer implement or by means of a spring enclosing the foot of the exchangeable borer implement. A further disadvantage is that the springs each exert a transverse force on the exchangeable borer implement which further influences the positioning of the exchangeable borer implement. An additional risk associated with the known conical connection is that individual exchangeable borer implements can inadvertently release or disengage depending on the operational conditions and on the care exercised in inserting the exchangeable borer implement.
These disadvantages are circumvented in an exchangeable borer implement arrangement known from Swiss Patent No. 549,682. Here, the exchangeable borer implements, which have cylindrical shafts, are inserted directly into close fitting bores in the borer rail. The close fitting bores for the exchangeable borer implements intersect other bores in the borer rail which each accept a screw. The part of the shaft inserted in the close fitting bore features a flat or flattened region against which presses a conical surface of the screw which is screwed into the borer rail in order to connect the exchangeable borer implement with the rail in an accurately oriented position. This known solution has the following substantial flaws or shortcomings. The fixation by means of a screw requires a large expenditure of time when the exchangeable borer implement is replaced, and as a consequence of frequent replacement of exchangeable borer implements the very fine thread is subject to excessive wear. The stop which determines the axial insertion depth of the exchangeable borer implement is formed by an inclined flank or ramped termination of the flat or flattened region. It is therefore not suitable for a precise axial positioning of the exchangeable borer implement.